Knives used on rotary disc mowers contact the crop material at high speeds, in order to cut effectively. This results in inherent dulling and wear. At times these knives contact other objects such as the ground, rocks etc. causing additional wear. As a result the knives must routinely be maintained.
The knives are pivotally mounted to discs, in a manner to reduce impact loading on the sharpened edge when striking an obstacle. FIGS. 1–4 illustrate a prior art mounting arrangement. Mower disc assembly 10 includes knife adapter 30 that is attached to the bottom side of disc body 20, retained with bolt 15 which passes through aperture 26 of disc 20 and into threaded aperture 36 of knife adapter 30. The knife adapter 30 can alternatively be welded to disc body 20. Knife adapter 30 further includes a cylindrical aperture 32 that is located concentric with a cylindrical aperture 22 of the disc body 20, together defining the pivot axis of knife 50. Knife 50 includes a cylindrical aperture 52, sized to allow sleeve portion 12 of bolt 14 to pass through allowing sufficient clearance so that the knife 50 will pivot freely. The mounting arrangement is completed by installing bolt 14 through the aperture 52 of the blade 50, then through the aperture 32 of knife adapter 30, and finally through aperture 22 of disc body 20, and into its mating nut 16.
The top side of the disc body 20 is in contact with the material being cut, functioning to lift and propel the cut material away from the knife. It is exposed to significant wear, along with any components located on the top side of the disc 20, such as nut 16. If nut 16 is subjected to sufficient wear, the hex configuration of its outer surface can be degraded to the point that a wrench no longer mates adequately to allow removal. In order to protect the nut 16 from this excessive wear prior art mounting arrangements have included a wear protector 17 mounted on the top of the disc body, to protect the nut 16 from this excessive wear.
Disc 20 is adapted to provide for this mounting arrangement by providing mounting surface 24 on disc body 20 for supporting wear protector 17. The disc 20 further includes a transition area to the raised portion 28. This raised portion 28 tapers such that at the far outer diameter of the disc 20, it does not exist. At lesser diameters the raised portion is increasingly larger. This raised portion 28, and the transition area between it and the mounting surface 24, provides protection for bolt 15, which thus does not require a wear protector.
The knife adapter 30 often includes a tab 34 that prevents full rotation of the knife 50, in order to control its location, in order to avoid interference with other components of the machine.
This mounting arrangement requires that the several pieces be disassembled with wrenches in order to maintain the knives which is costly and difficult due to the number of knives on a machine.